/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:		arm_scale_q7.c
*
* Description:	Multiplies a Q7 vector by a scalar.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated
*
* Version 0.0.7  2010/06/10
*    Misra-C changes done
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupMath
 */

/**
 * @addtogroup scale
 * @{
 */

/**
 * @brief Multiplies a Q7 vector by a scalar.
 * @param[in]       *pSrc points to the input vector
 * @param[in]       scaleFract fractional portion of the scale value
 * @param[in]       shift number of bits to shift the result by
 * @param[out]      *pDst points to the output vector
 * @param[in]       blockSize number of samples in the vector
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.7 format.
 * These are multiplied to yield a 2.14 intermediate result and this is shifted with saturation to 1.7 format.
 */

void arm_scale_q7(
    q7_t* pSrc,
    q7_t scaleFract,
    int8_t shift,
    q7_t* pDst,
    uint32_t blockSize)
{
	int8_t kShift = 7 - shift;                     /* shift to apply after scaling */
	uint32_t blkCnt;                               /* loop counter */

#ifndef ARM_MATH_CM0

	/* Run the below code for Cortex-M4 and Cortex-M3 */
	q7_t in1, in2, in3, in4, out1, out2, out3, out4;      /* Temporary variables to store input & output */


	/*loop Unrolling */
	blkCnt = blockSize >> 2u;


	/* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
	 ** a second loop below computes the remaining 1 to 3 samples. */
	while(blkCnt > 0u) {
		/* Reading 4 inputs from memory */
		in1 = *pSrc++;
		in2 = *pSrc++;
		in3 = *pSrc++;
		in4 = *pSrc++;

		/* C = A * scale */
		/* Scale the inputs and then store the results in the temporary variables. */
		out1 = (q7_t)(__SSAT(((in1) * scaleFract) >> kShift, 8));
		out2 = (q7_t)(__SSAT(((in2) * scaleFract) >> kShift, 8));
		out3 = (q7_t)(__SSAT(((in3) * scaleFract) >> kShift, 8));
		out4 = (q7_t)(__SSAT(((in4) * scaleFract) >> kShift, 8));

		/* Packing the individual outputs into 32bit and storing in
		 * destination buffer in single write */
		*__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4);

		/* Decrement the loop counter */
		blkCnt--;
	}

	/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
	 ** No loop unrolling is used. */
	blkCnt = blockSize % 0x4u;

	while(blkCnt > 0u) {
		/* C = A * scale */
		/* Scale the input and then store the result in the destination buffer. */
		*pDst++ = (q7_t)(__SSAT(((*pSrc++) * scaleFract) >> kShift, 8));

		/* Decrement the loop counter */
		blkCnt--;
	}

#else

	/* Run the below code for Cortex-M0 */

	/* Initialize blkCnt with number of samples */
	blkCnt = blockSize;

	while(blkCnt > 0u) {
		/* C = A * scale */
		/* Scale the input and then store the result in the destination buffer. */
		*pDst++ = (q7_t)(__SSAT((((q15_t) * pSrc++ * scaleFract) >> kShift), 8));

		/* Decrement the loop counter */
		blkCnt--;
	}

#endif /* #ifndef ARM_MATH_CM0 */

}

/**
 * @} end of scale group
 */
